1. Field of the Invention
The present invention relates to an exposure device for forming patterns on a surface of a flat-sheet material, including a substrate for an electronic circuit, a glass substrate for an LCD and a glass element substrate for a PDP.
2. Description of the Related Art
In general, substrates for electronic circuits or printed circuits are applied to electronic instruments such as portable phones or various types of PCs. On a substrate of this type, multiple fine patterns, lands and via-holes tend to be formed with great precision. In addition, an exposure device which forms such miniature patterns is required to handle many different types of substrates in a short period. In order to follow the trend as well as meet the requirement, an exposure device uses high-intensity and short-wavelength light. However, a general type, that is, contact or projection type exposure device needs to contain masks to form patterns. Accordingly, multiple different masks are prepared depending on the types of substrates to be processed. However, those masks are hard to prepare, exchange or maintain, thus making it difficult to treat many different substrates efficiently.
Because of this disadvantage, interest is growing in a direct type exposure system and a device incorporating this system. This direct type exposure system has digital micro-mirror devices (DMDs) composed of many reflective mirrors, and moves those mirrors based on the CAD data. As a result, desired patterns are transferred from CAD data to a substrate by means of light beams, so that masks are unnecessary (see JP A 2006-113413, JP A 2006-343684 and JP A 2006-337475).
However, a typical direct type exposure device tends to have a low reaction speed in forming patterns, because its light source is a laser of short wavelength such as 405 nm. Hence, this property may cause the deterioration of the production capacity.
In addition to the low production capacity, a typical direct exposure device involves a cost increase. This is because it is equipped with many spatial light modulation elements for treating large-size substrates. If high-intensity light beams are irradiated to those many spatial light modulation elements, then many light sources are required, thus leading to the increase in the material costs.
Taking the above description into account, the present invention has been conceived. An object of the present invention is to provide a direct type exposure device which works efficiently. An additional object of the present invention is to present a direct type exposure device which has a few optical sources and many digital micro-mirror devices (DMDs) functioning as spatial light modulation devices. A further object of the present invention is to produce a direct type exposure device which is designed to monitor the intensity of its light source(s).